In general, a fuel cell has a structure in which the unit cells are stacked. In each of the fuel cells, both surfaces of a membrane electrode assembly (MEA) are held by a pair of separators with gaskets interposed therebetween. A stacked body of the unit cells is generally referred to as a stack.
Among component parts of the fuel cell, the membrane electrode assembly includes a solid polymer electrolyte membrane. A cathode electrode and an anode electrode are disposed on both surfaces of the solid polymer electrolyte membrane. Each of these cathode electrode and anode electrode has a catalyst layer and a gas diffusion layer.
Meanwhile, among the component parts of the fuel cell, the separator is made of a plate-shaped member having conductivity. A plurality of flow path walls are formed on one surface of the separator. The plurality of flow path walls are flow path walls for causing an oxidizing gas to flow between the one surface of the separator and the cathode electrode. A plurality of flow path walls are also formed on the other surface of the separator. The plurality of flow path walls formed on the other surface are flow path walls for causing a fuel gas to flow between the other surface and the anode electrode. Holes serving as a gas introduction path and a gas discharge path are formed at both ends of the flow path walls, respectively. The holes respectively formed at both ends of the flow path walls communicate with each other when the stack is configured. The holes communicating at both ends of the unit cells form a series of gas introduction path and a series of gas discharge path.
In such a fuel cell, hydrogen is decomposed into a hydrogen ion and an electron at the anode electrode. The hydrogen ion passes through the solid polymer electrolyte membrane to the cathode electrode, and the electron passes through a plurality of flow path walls which come in contact with the cathode electrode and moves to the cathode electrode. The cathode electrode causes the hydrogen ion and the electron to react with oxygen to generate water. In addition, the water generated at the cathode electrode side is reversely diffused toward the anode electrode side through the solid polymer electrolyte membrane.
In a conventional method, a plurality of protrusions are formed between flow path walls of a separator and holes of the separator, that do not couple with the flow path walls. The plurality of protrusions of the separator support a gasket.